How MySQL modifies field type and field length

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mysql Modify field type and field length

1、 Modify field type

2、 Modify field length

Modify the length of a field in the database table

mysql Modify field type and field length 1、 Modify field type

Format ：alter table Table name modify column Field name type ;

example ：

take users Tabular registerTime Change the field to datetime type ;

alter table users modify column registerTime datetime;2、 Modify field length

Format ：alter table Table name modify column Field name type ( length );

example ：

take users Tabular username Change the field to varchar type , The length is 30 Bytes ;

alter table users modify column username varchar(30); Modify the length of a field in the database table // Create a temporary table CREATE TABLE TMP_TABLE(CUSNO CHAR(10))// modify TMP_TABLE In the table CUSNO Length of field ALTER TABLE TMP_TABLE MODIFY CUSNO CHAR(20)

The above is personal experience , I hope I can give you a reference , I also hope you can support the software development network .